# NTSB FTW86FA007: Bell 206L-1, N515EH, Tomball, TX, October 7, 1985

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Field investigation · Final report
- Date: October 7, 1985, 08:10 local (13:10 UTC)
- Place: Tomball, TX
- Coordinates: 30.090936, -95.609916 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=30.0909&lon=-95.6099&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 21871
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW86FA007
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/21871/pdf
- Page: https://openairdocs.org/ntsb/FTW86FA007

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Loss of engine power(total) - mech failure/malf, climb - to cruise
  - turboshaft engine,gas generator turbine shaft - disconnected (cause)
  - turboshaft engine,gas generator turbine shaft - fatigue (cause)
- Forced landing, descent - emergency
- Hard landing, landing - flare/touchdown
  - airport facilities,runway/landing area condition - none suitable (contributing factor)
  - autorotation - performed, pilot in command

## Analysis

ACFT WAS SUBSTANTIALLY DAMAGED AS A RESULT OF A HARD LANDING DURING AN EMERGENCY AUTOROTATION FOLLOWING A COMPLETE POWER LOSS. THE POWER LOSS OCCURRED AS A RESULT OF AN UNCONTAINED FAILURE OF THE NO. 1 TURBINE WHEEL. THE WHEEL BURST AS A RESULT OF A FATIGUE FAILURE OF THE TURBINE TO COMPRESSOR COUPLING WHICH ALLOWED THE SHAFT TO DECOUPLE. WHEN THE TURBINE SECTION DECOUPLED THE ENGINE EXPERIENCED AN OVERSPEED. THE ORGIN OF THE FATIGUE FRACTURE WAS FOUND IN THE SCALLOP AREA ON THE TURBINE END OF THE SHAFT. THE ENG FAILURE OCCURRED AT LOW ALTITUDE ON DEPARTURE AND THE PLT HAD TO MANEUVER THE ACFT IN ORDER TO MAKE THE ONLY AVAILABLE FORCED LANDING AREA.

## Aircraft

- Registration: N515EH (not matched to a registry record)
- Reported make and model: BELL 206L-1
- Category: Helicopter
- Serial number: 45364
- Airframe hours: 2764
- Engines: ALLISON 250-C28B 435 horsepower turbo shaft
- Damage: Substantial damage
- Flight: Positioning, Part 91
- Operator: Dhl Airways, Inc.
- Registered owner: Helicopters Unlimited
- Airworthiness certificate: Standard, Normal
- Last inspection: AAIP, September 23, 1985, 10 hours before
- Destination: IAH, HOUSTON, TX
- Flight plan: VFR
- Airport: DWH, David Wayne Hooks

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 34; commercial; airplane ratings: single-engine land; medical: class 1, valid medical--no waivers/lim.; seat: right; flight hours: 4,333 total, 3,444 in this make and model, 4,143 as pilot in command, 155 in the last 90 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 50° at 5 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 54 °F, dew point 50 °F
- Altimeter: 30.00 inHg
- Observed at: CXO, 15 nm away

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19851007049699A](https://openairdocs.org/incident/19851007049699A), Oct 7, 1985: Bell 206L1, Tomball, TX, Substantial damage. Turbine coupler failed from metal fatigue. Aircraft was damaged from hard touchdown during emergency landing.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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